April 21, 2020  |  

A novel plasmid carrying carbapenem-resistant gene blaKPC-2 in Pseudomonas aeruginosa.

A carbapenem-resistant Pseudomonas aeruginosa strain PA1011 (ST463) was isolated from a patient in a surgical intensive care unit. PCR detection showed that PA1011 carried the blaKPC-2 gene. A plasmid was isolated and sequenced using the Illumina NextSeq 500 and PacBio RSII sequencing platforms. The plasmid was named pPA1011 and carried the carbapenem-resistant gene blaKPC-2. pPA1011 was a 62,793 bp in length with an average G+C content of 58.8%. It was identified as a novel plasmid and encoded a novel genetic environment of blaKPC-2 gene (?IS6-Tn3-ISKpn8-blaKPC-2-ISKpn6-IS26).


April 21, 2020  |  

Carbapenem-Resistant Pseudomonas aeruginosa at US Emerging Infections Program Sites, 2015.

Pseudomonas aeruginosa is intrinsically resistant to many antimicrobial drugs, making carbapenems crucial in clinical management. During July-October 2015 in the United States, we piloted laboratory-based surveillance for carbapenem-resistant P. aeruginosa (CRPA) at sentinel facilities in Georgia, New Mexico, Oregon, and Tennessee, and population-based surveillance in Monroe County, NY. An incident case was the first P. aeruginosa isolate resistant to antipseudomonal carbapenems from a patient in a 30-day period from any source except the nares, rectum or perirectal area, or feces. We found 294 incident cases among 274 patients. Cases were most commonly identified from respiratory sites (120/294; 40.8%) and urine (111/294; 37.8%); most (223/280; 79.6%) occurred in patients with healthcare facility inpatient stays in the prior year. Genes encoding carbapenemases were identified in 3 (2.3%) of 129 isolates tested. The burden of CRPA was high at facilities under surveillance, but carbapenemase-producing CRPA were rare.


April 21, 2020  |  

A Phage-Like Plasmid Carrying blaKPC-2 Gene in Carbapenem-Resistant Pseudomonas aeruginosa.

Background: Lateral gene transfer plays a central role in the dissemination of carbapenem resistance in bacterial pathogens associated with nosocomial infections, mainly Enterobacteriaceae and Pseudomonas aeruginosa. Despite their clinical significance, there is little information regarding the mobile genetic elements and mechanism of acquisition and propagation of lateral genes in P. aeruginosa, and they remain largely unknown. Objectives: The present study characterized the genetic context of blaKPC-2 in carbapenem-resistant P. aeruginosa strain BH9. Methods:Pseudomonas aeruginosa BH9 sequencing was performed using the long-read PacBio SMRT platform and the Ion Proton System. De novo assembly was carried out using the SMRT pipeline and Canu, and gene prediction and annotation were performed using Prokka and RAST. Results:Pseudomonas aeruginosa BH9 exhibited a 7.1 Mb circular chromosome. However, the blaKPC-2 gene is located in an additional contig composed by a small plasmid pBH6 from P. aeruginosa strain BH6 and several phage-related genes. Further analysis revealed that the beginning and end of the contig contain identical sequences, supporting a circular plasmid structure. This structure spans 41,087 bp, exhibiting all the Mu-like phage landmarks. In addition, 5-bp direct repeats (GGATG) flanking the pBH6 ends were found, strongly indicating integration of the Mu-like phage into the pBH6 plasmid. Mu phages are commonly found in P. aeruginosa. However, for the first time showing a potential impact in shaping the vehicles of the dissemination of antimicrobial (e.g., plasmid pBH6) resistance genes in the Pseudomonas genus. Conclusion: pBH6 captured the Mu-like Phage BH9, creating a co-integrate pBH6::Phage BH9, and this phage-plasmid complex may represent novel case of a phage-like plasmid.


April 21, 2020  |  

Genome plasticity favours double chromosomal Tn4401b-blaKPC-2 transposon insertion in the Pseudomonas aeruginosa ST235 clone.

Pseudomonas aeruginosa Sequence Type 235 is a clone that possesses an extraordinary ability to acquire mobile genetic elements and has been associated with the spread of resistance genes, including genes that encode for carbapenemases. Here, we aim to characterize the genetic platforms involved in resistance dissemination in blaKPC-2-positive P. aeruginosa ST235 in Colombia.In a prospective surveillance study of infections in adult patients attended in five ICUs in five distant cities in Colombia, 58 isolates of P. aeruginosa were recovered, of which, 27 (46.6%) were resistant to carbapenems. The molecular analysis showed that 6 (22.2%) and 4 (14.8%) isolates harboured the blaVIM and blaKPC-2 genes, respectively. The four blaKPC-2-positive isolates showed a similar PFGE pulsotype and belonged to ST235. Complete genome sequencing of a representative ST235 isolate shows a unique chromosomal contig of 7097.241?bp with eight different resistance genes identified and five transposons: a Tn6162-like with ant(2?)-Ia, two Tn402-like with ant(3?)-Ia and blaOXA-2 and two Tn4401b with blaKPC-2. All transposons were inserted into the genomic islands. Interestingly, the two Tn4401b copies harbouring blaKPC-2 were adjacently inserted into a new genomic island (PAGI-17) with traces of a replicative transposition process. This double insertion was probably driven by several structural changes within the chromosomal region containing PAGI-17 in the ST235 background.This is the first report of a double Tn4401b chromosomal insertion in P. aeruginosa, just within a new genomic island (PAGI-17). This finding indicates once again the great genomic plasticity of this microorganism.


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